High frequency cable system



March 31, 1936. L, WALTER 2,036,002

HIGH FREQUENCY CABLE SYSTEM Filed Jan. '7, 1933 3 Sheets-Sheet lINVENTOR- LUDWIG WALTER ATTORNEY- Marcia w l 1936., L. WALTER HIGHFREQUENCY CABLE SYSTEM Filed Jan. '7, 1933 3 Sheets-Sheet 2 INVENTOR-LUDWIG WALTER BY 7% m ATTORNEY- L' TE i2 HIGH FREQUENCY CABLE SYSTEMFiled Jan. 7, 1933 3 Sheets-Sheet 5 INVENTOR- LUDWIG WALTER BY .wg /a/ATTORNEY- Patented Mar. 31, 1936 UNITED STATES PATENT OFFICE LudwigWalter, Berlin, Germany, assignor to Telefunken Gesellschaft furDrahtlose, Telegraphic in. b. H., Berlin,

tion of Germany Germany, a corpora- Application January 7, 1933, SerialNo. 650,645 In Germany January 9, 1932 5 Claims.

This invention relates to an improved high frequency cable system, bymeans of which an effective change of circuits can be made withoutimpairing the eificiency of the system.

The object of this invention is to provide a circuit arrangement adaptedto unite at will the various radio frequency downleads of a system whichcomprises a plurality of such energy-feed leads, with any of the variousenergy-feed leads of another system of similar nature. Such a scheme maybe used, for instance, in receiving equipments for radio intelligencetransmission on short waves. Where these are of relatively large size,they usually contain a comparatively large number of aerials and-also aplurality, but mostly dissimilar number, of receivers, and there arisesapractical requirement to connect any one of the receivers with anydesired antenna. The connecting link between the antennae and thereceivers, as is well known in the art, is effected by way of radiofrequency energy-feed leads or downleads, and these mustbe so disposedand proportioned that an optimum propagation of the waves will beassured. A similar scheme could be carried into practice'also intransmitter plants.

Another object of this invention is to provide an improved couplerdevice adapted to connect the concentric radio frequency downleads fromthe antenna to the receivers, whereby the joining both of the externalas Well as of the internal conductor isaccomplishable in the simplestpossible manner by a mere manipulation of the outer conductor. Theessential feature consists in that by the closure of look, by means ofwhich the two tubular outers are joined with each other, there isexerted at-the same time the requisite contact pressure between theabutting inner conductors.

Another object of this invention is to provide an improved highfrequency cable for use in the improved antenna system wherein the innerconductor is disposed internally within the outer conductor by means ofimproved insulating'elements or bodies being spaced apart from oneanother so as to minimize the capacity of the cable.

Still another object of this invention is to provide the high frequencycable with improved insulated disks having radial slots for retainingthe central conductor within the outer metallic sheath.

In change-over antenna switching arrangements of the kind suggested inthe prior art for the said purpose, optimumconditions could not bepreserved in all junctions thus-established, for instance, because dummyleads or parts of leads were unavoidable, and these act-likeconcentrated (lumped) capacities becoming a source of disturbance in thetuning of the downleads. The problem of providing an arrangement thatwill measure up to all requirements is aggravated still further onaccount of the fact that the feed-leads in the majority of cases consistof concentric radio frequency energy-feed or downlead cables of the kindknown in the art. In a scheme of this sort each internal conductor mustbe perfectly shielded in reference to all of the other conductorscomprised in the arrangement,in order that no spurious coupling may bepermitted between them. Finally, this demand must be made that eachjunction between an aerial and a receiver should contain a minimumnumber of contacts, preferably but one, seeing that each contactrepresents a potential source of trouble in the case of incomingcurrents of a small value as here concerned.

In order that all of these requirements may be fulfilled, according tothe present invention, all of the feedleads of one system, and similarlythose of the second system, are separately conveyed in the arrangementin such a way that from the ends of the leads of one system to theterminals of the leads of the second system connecting leads may beestablishable of a kind that will be of the same, or nearly the same,length between any point of one system and any point of the other.

One practical embodiment of this basic idea resides in that the ends orterminals of one system terminate upon the circumference of a circle orat the corners or apexes of a regular polygon, and that similarly theends of the second system are located along a second circle or polygonbeing disposed co-axially in reference to the first system. All thatwill then be necessary and governing is to choose the distance betweenthe two circles or the two polygons compared with the diameter in such away that the demand-of approximately equal length between any point ofone system to any point of the other will be satisfied.

For establishing connection between the two systems, according to thisinvention, flexible junction wires are used, the length of which mustexceed by a certain amount the intervening distance between the twocircles of the systems, the

said junction wires being passed through the air along an arc-from onesystem to the other.

High frequency cables are known in the prior art of a kind in which, manouter sheath or casing or shell serving as a protection againstmechanicaldamage, one-or moreconductors are disposed in such a way thatthey are spaced apart from one another and from the outer shell by theaid of rings or of beads made of insulator material. Similar cables havebeen used also in the form of concentric radio frequency energy lines orleads (downleads) in which the outer tubular shell and an inner leadcoaxially arranged therein serve as conductors of the current.

In such radio frequency cables it is of advantage, in order that thesame may be of low capacity, to mount the insulating rings or diskssupporting the internal conductor spaced a certain distance apart.Several means have been disclosed in the art in order to insureconstancy of distance between the insulating pieces in the interior ofthe cable. Now, the present invention discloses novel means adapted tothe said end, which are of a nature to insure a particularly lowcapacity for the cable inasmuch as distinct spacer elements or piecesfor the insulating bodies are avoided, and this makes for greaterconvenience and simplicity in the construction of the cable. Accordingto the invention, the insulating pieces of the radio frequency cable arespaced apart from one another by continuous wires attached thereto.These spacer wires could also be used as current conductors in thecable.

Referring now to the drawings,

' Fig. 1 is a front elevation of the improved cable system;

Fig. 2 is a plan view of the lower portion of my improved cable system;

Fig. 3 is a detailed longitudinal cross-section of the improved couplerdevice;

Fig. 4 is a side elevation of Fig. 3 showing the bayonet joint forestablishing a firm coupling between the conductors;

. Fig. 5 is a cross-section of the cable showing the method ofpreventing rotation of the cable when turning the cap nut, the sectionbeing taken on line A-A of Fig. 3;

Fig. 6 is a longitudinal cross-section of the improved high frequencycable;

Fig. 7 is a cross-sectional view of Fig. 6;

Fig. 8 is a cross-sectional view similar to Fig. 7 except a plurality ofcentral conductors are shown located within the outer conductor;

Fig. 9 is a longitudinal cross-section of the improved high frequencycable with suitable insulating spacers;

Fig. 10 is a cross-sectional view of Fig. 9, and

Fig. 11 is a cross sectional view similar to Fig. 10 except a pluralityof central conductors are shown located within the outer conductor andretained by means of insulated disks having radial slots.

An exemplified arrangement according to the invention is shown by Figs.1 and 2, wherein there is shown arranged a suitable frame or rack in theform of a top circle I to which the downleads 2 of one system, say, thepart of the leads coming from the receivers, are brought, the same.being secured thereon in such a way that their terminal heads 3 aredirected downwardly. Below the circle, upon the floor or ground, andalso in the shape of a circle of more or less large diameter, there isan assembly or bank of vertical concentric pipe pieces which representthe terminal parts of the downleads 5 of the second system and which,for instance, may be brought down from the antennae. The said pipepieces have at their upper ends inwardly directed terminal heads 8.Connection between the upper and the lower systems is established bymeans of the flexible junction or coupling pieces indicated at I, thelatter consisting likewise of concentric energy-feed cables and beingdesigned to be fitted with their suitably shaped terminals into theterminal couplings or sockets of the upper and the lower lead systems.

A detailed description of the coupling will be given later.

By choosing a form of construction for the terminals of the upper andthe lower annular system, conditions can be made so that the flexibleconnector wires or radio frequency cables, no matter what the particularjunction, will have substantially only one general downward curvaturewith only a single elbow or bend at the lower end. This fact is ofspecial importance on the ground that the connectors, owing to theirconcentric construction as energy-feed leads, are capable of beingflexed only along a definite and minimum'radius. In spite of a greatnumber of possible couplings inside the systems, they will experienceonly a minimum amount of mechanical stress as a result of the particulardisposition thereof as hereinbefore described/ Ihe upper ends of theflexible connector leads in the switching or antenna couplingarrangement, that is to say, at the terminal ends brought from thereceiver equipments, may permanently stay connected once they have beenfitted or joined thereto, in fact, it is only the lower ends that haveto be disengaged for the change of connections, and the practical resultis that the downleads as a whole comprise only one disengageable contactpoint. If in this arrangement all of the proportions are properlychosen, and if the flexible conductor pieces are so placed as to coverthe shortest possible distance, it will be seen that no tangling willoccur even where the number of leads is large.

One exemplified embodiment of the coupling device is shown in Fig. 3wherein the two outer conductors H and Ila terminate in tubular bushingsl2- and I211. The inner conductors i3 and l3a terminate in head piecesl4 and Ma. These latter are held inside the terminal bushings I 2 and12a of the outer conductors by the aid of conical insulating pieces 15and 15a. The said head or inner conductor terminal pieces l4 and Maprotrude in a tipor dome-like fashion from the face of the saidinsulating pieces. To unite the two energy-feed leads they are placedadjacent to each other with their anterior faces so that the tips of thehead pieces l4 and Ma of the inner conductors, and the edges of thetubular bushings l2 and 12a of the outer conductors come to abut againstone another, with a certain amount of clearance being provided for thelatter, For establishing firm coupling a sort of bayonet joint [0 asshown in Fig. 4, is used, constituted by the cap nut it which is heldrotatably upon the ferrule 20a of the tubular bush 12a. of theenergy-lead and whose segmental projections ll come'to engage overcorresponding segments I8 on the ferrule 20 of tubular bushing E2 of therespective other lead, the said segments ll and I8 being wedge-shaped(conical) in the direction of rotation so that by approximately rotationof the cap nut IS the connection is effected with an incidentaltightening (pulling) of the downleads. action that the requisitepressure is produced whereby the abutting head pieces M and Ma of theinner energy leads are pressed together so that a safe connection isestablished also between the inner conductors.

It is by virtue of this tightening In order that when turning the capnut for the purpose of joining the energy feed-leads, one of the leadsmay be prevented from participating in such rotation, the end faces ofthe terminal bushings are furnished with tooth rims H), as shown in Fig.5. When the two leads are fitted together, the said teeth will come tointer-engage. Thus, if one of the leads is fixedly mounted with itsterminal bushing secured in place, then the second mobile lead can bebrought to a point at close proximity thereto in any desired positionwithout it being necessary to first turn it into a definite position inreference to the fixed conductor.

The spacing of the insulator elements of the high frequency cable insidethe tubular shell is secured in an extremely simple manner by theinsulator disks threaded upon the inner conductor being prevented frombeing shifted out of position by pinched or squashed points in theconductor bilaterally of the disks.

An arrangement of such insulator disks is shown by way of example inlongitudinal crosssection Fig. 6, and the cross-section view Fig. '7.The outer conductor of the radio-frequency cable, for instance, consistsof the leaden sheath or shell 3|, the inner one consisting of theco-axial wire 32, the latter being held in position by the aid ofinsulator disks 33 consisting of a suitable sort of insulation material,such as glass, porcelain, etc, and being spaced suitable distancesapart. Upon both sides or faces of the insulator disk 33 is a squash 34in the conductor 32, so that the latter is unable to work its waythrough the bore of the disk 33, because the latter is just adapted tothe gauge of the wire.

Instead of just one inner conductor, it would be feasible to arrangealso a plurality thereof in the radio frequency cable as shown by way ofexample in the cross-sectional view Fig. 8. In this instance, inaddition to the central conductor 32, there have been passed threeadditional conductors 35, 36, 31, through suitable holes formed in theinsulator disks. In this case, these wires 35, 36, 31, could constitutethus the outer of a concentric energy-feed line (downor uplead), shell3| in that instance serving solely as a protector. But it is alsofeasible to accommodate only two or three conductors in the interior ofthe tubular shell 3|. A cable containing a plurality of such conductorscould, for instance, serve for the feeding or supply of several circuitsor as a three-phase transmission line. The spacing apart of theinsulation disks may be secured and insured, where a plurality ofconductors are concerned, by squashes provided in all of the conductors,though, if desired, securing by a single set of squashes, say in thecentral conductor, may sufiice.

The manufacture of a cable of the kind here disclosed is particularlysimple. For instance, first a chain comprising the inner conductor withinsulator disks threaded thereon may be formed, whereupon, in anuninterrupted operation, the leaden sheath or shell 3| is formed bypressure around the same.

An embodiment of such a cable is shown in Fig. 9 in longitudinal sectionand in cross-section by way of example. The cable consists of the outertubular conductor 5| and the inner co-axial conductor 52. The tubularconductor 5| most preferably consists of a leaden sheath or shell whichconstitutes at the same time the protector of the cable againstmechanical damages. Threaded upon the inner conductor 52 are theinsulator pieces 53, by the aid of which co-axial position inside shell5| is secured and preserved. The insulator disks 53 consist of asuitable insulation material such as glass, porcelain, steatite, and thelike. In order to insure proper spacing between the said insulator disks53, wires 54, 55, 56, are attached thereto, connection beingaccomplishable in any desired way. It is conven ient to provide theinsulator disks 53 with slots, and to press-fit the spacer wires 54, 55,56, op tionally consisting of copper into the said grooves.

As shown in Fig. 10, the securing of the spacer wires 54, 55, 56, iseffected directly upon the circumferences of the insulator disks 53. Asa consequence, these wires 54, 55, 56 come to make direct contact withthe outer lead shell 5| so that they serve conjointly with the latterfor the carrying and conduction of the current, with the result thatthey promote the conductivity of the outer conductor.

However, it is also possible to press-fit the spacer wires 54, 55, 55,into slots formed in the insulator disks 53 being of greater depth, in aWay shown, for instance, in Fig. 11 in cross-section, with the resultthat the spacer wires do not make contact with the outer shell. In thisinstance, for example, the wires 54, 55, 56, conjointly could constituteone conductor, while 52 represents the second conductor, the outer shellin that case serving solely for mechanical protection. In a cablecomprising a plurality of such inner conductors, the latter could servealso for the supply of a plurality of different circuits, say, as athree-phase current transmission cable.

A cable of the kind hereinbefore described may be manufacturedparticularly conveniently by that the insulating disks threaded oralined upon the conductor 52 are first press-fitted together with thewires 54, 55, 56, whereupon the leaden shell or case 5| is press-fittedaround the chain or rosary thus produced in an uninterrupted process.

In cables of the kind as described it is of advantage to provide theinner conductor, i. e., the central conductor 52 and the wires 54, 55,55, when they do not make contact with the outer shell, with a suitablecoat of varnish or other insulation means. In this way, the risk of ashort-circuit being produced between the conductors as a result of acompression of the lead shell between two insulation bodies due tomechanical damage to the cable, is obviated.

Although this invention has been described and shown in a particularform and arrangement of parts, it should be understood it is capable ofembodiment in other and different forms and not limited to those shown,except as such limitations are clearly imposed by the appended claims.

I claim:

1. A switching arrangement adapted to insure at will connection betweenthe radio-frequency downleads of a short wave system comprising aplurality of leads forming a first system, a corresponding plurality ofleads forming a second system and a flexible coupling lead for joiningsaid first and second systems, with this characteristic feature that theterminal points of the downleads of the first system and similarly theleads of the second system are each placed in a circle, one system beinglocated above the other so that from any terminal point of one systemand each terminal of the other system it will be possible to accommodatepractically equal lengths of said flexible coupling leads.

2. An antenna switching arrangement comprising a plurality of concentricenergy feed cables arranged in a circular manner on a frame, wherein thejunction leads connecting an upper and lower system consist of aplurality of flexible concentric cables each of which terminates with aterminal socket fitted thereon, with this characteristic feature thatthe junction leads between the terminal sockets of the flexibleconcentric cables connecting the upper and lower systems is arranged toinsure the formation of a general downward curvature at the lower end ofthe junction lead which will be substantially in the shape of an elbow.

3. An antenna short wave switching arrangement comprising a plurality ofconcentric conductors, said conductors divided into an upper and lowersystem, the lower system located near the ground, the conductors beingarranged to 4. An antenna short wave switching arrangement comprising aplurality of concentric conductors, said conductors divided into anupper and lower system, the lower system located near the ground, theconductors being arranged to form the periphery of a regular polygon,the upper system arranged above said lower system, forming a regularpolygon with a periphery similar to said lower system, a flexibleconnection joining said systems, said flexible connection comprisingconcentric conductors having detachable end terminals with a bayonetjoint locking means for detaching said flexible conductor from saidupper and lower systems.

. 5. An antenna short wave switching arrangement comprising a pluralityof concentric conductors, said conductors divided into an upper andlower system, the lower system located near the ground; the conductorsbeing arranged to form the periphery of a regular polygon, the uppersystem arranged above said lower system, forming a regular polygon witha periphery similar to said lower system, a flexible connection joiningsaid systems, said flexible connection comprising concentric conductorshaving detachable end terminals witha tooth-like rim and a rotatable capfor detaching said flexible conductor from said upper and lower systems.

- LUDWIG WALTER.

